Iinuton



W. MAUSS.

PERCUSSIVE ENGINE.

APPLICATION FILED NOV-6.1915.

1 309,649. Patented July 15, 1919.

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W. MAUSS.

PERCUSSiVE ENGINE.

APPLICATION mu) NOV. 6. 1915.

1,309,649, Patented July 15, 1919.

2 SHEETS-SHEET 2.

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WILHELM MAUSS, OF JOHA'NNES BURG, TRANSVAAL, SOUTH AFRICA.

PERCUSSIVE ENGINE.

Specification of Letters Patent.

Patented July 15, 1919.

Application filed November 6, 1915. Serial No. 59,982.

To all whom it may concern Be it known that I, VILIIELM Mnuss, a British subject, and a resident of Commercial Exchange Buildings, Johannesburg, Transvaal Province, Union of South Africa, have invented certain new and useful Improvements in Percussive Engines, of which the following is a specification.

The present invention relates to fluid actuated rock drills channeling machines and coal cutters which are designed for rapid and continuous reciprocation of a free piston which is propelled without material retardation throughout its full normal stroke, and in which the distribution of working fluid is effected by a valve which is con-' trolled solely by the working piston and so as to be thrown according to the position of the latter relatively to the cylinder.

The period of the cycle of such a machine may be shortened and the number of blows per minute consequently increased by causing the piston on approaching the rearward end of its stroke to compress a body of the working fluid which is to be used for effecting the next forward stroke and which is already present in the rear cylinder chamber at working pressure; said body being of substantial extent but limited to that contained in the rear cylinder chamber with or without the air passage connected thereto. Since however there is always loss by leakage and absorption of heat by the cylinder walls, the fluid so compressed tends on reexpansion to fall below the pressure from which it was initially compressed and so reduce the force available to propel the piston on its forward stroke.

To overcome this drawback the present invention provides in a machine as specified a non-return valve governing a fluid supply port which leads to and is constantly in communication with the rear cylinder chamber, said non-return valve being arranged to be closed by displacement of fluid from the rear cylinder chamber and being free at all times to open to pass fluid to said chamber when the pressureof the fluid on its supply side is not less than that of the fluid on its cylinder side. By the rear cylinder chamber is meant the chamber in which the rear working pressure face of the piston works and in which is contained the fluid which acts upon said pressure face to drive the piston on its blow stroke.

In the accompanying drawings,

Figure I shows an engine having continuous pressure on its rear piston face, and embodying one arrangement of the invention.

Fig. II is a similar view to Fig. I, but with the parts in a different position.

Figs. III and IV show the same typeof engine with the invention diflerently embodied.

Fig. V is a partial section plane taken on the line XX of Fig. I.

Referring to Figs. I and II the cylinder comprises a: large front chamber 1 and a smaller rear chamber 2. The piston correspondingly has a relatively large front member 3 and a smaller rear member 4, providing respectively the forward pressure area 5 and the rear pressure area 6.

The distributing valve 7 works in the valve chamber 8. It governs admission to and exhaust from the front cylinder chamber 1 and is arrai'iged closely contiguous thereto. 9 is an inlet port and 10 an exhaust port. 11 is a port from the valve chamber 8 to the front cylinder 1. During its reciprocation the valve alternately connects the cylinder port 11 to one or other of the ports 9 or 10.

Any suitable provision is made for actuating the valve 7. As shown, a passage 12 is carried from the front end of the valve chamber to the forward piston chamber 1 and a passage 13 from the rear of the valve chamber to the rear piston chamber 2. During the rearward movement of the piston, the rear end of the valve chamber is exhausted through the passage 18, the annular recess 14. around the piston, and the hole 15 in the cylinder wall. \Vorking fluid herein called air is admitted to the front end of the valve chamber from the front cylinder chamber through the passage 12, and the valve is consequently thrown backward as shown in Fig. II. Before the blow is struck the passage 12 is connected to atmosphere by the recess 11 and the hole 15; while air passes into the passage 13 and the valve is thrown forward again as in Fig. I.

Air is supplied to the rear cylinder chain ber by the port 16, one end of which is in permanent communication with the live air supply and the other end of which opens into said chamber some distance from the rear end of the cylinder. From said port a branch 17 extends to the extreme rear end of the cylinder. In said branch is fitted the non-return valve 18 which opens toward the cylinder.

In Fig. I the piston is shown as though it has just struck its blow. Live air is now acting on both piston faces 6 and 5 and the latter being of greater area the piston is forced back. During the first part of such backward movement air displaced from the cylinder 2 assists in feeding the front cylinder 1 rapidly and completely. The piston area 5 is considerably larger than the area 6 and the admission offull pressure air to the former is continued through the greater part of the rearward stroke so that the piston accelerates at a high rate during the greater part of said stroke.

When'the piston has moved back a certain distance as indicated by the full lines of Fig. II the valve 7 is thrown over and the front cylinder 1 is exhausted. At about the same moment the piston head 4 closes the port 16. The piston, having acquired considerable rearward momentum, continues to move backward to about the position inclicated by the dotted lines Fig. II, thereby compressing the air inclosed in the cylinder chamber 2. Said air being initially at work ing pressure is rapidly compressed to a high degree with the result that the piston is quickly stopped and restarted on the forward stroke with considerable momentum. When, during the reexpansion of the air, the pressure in the chamber 2 drops to that of the air supply, the valve 18 opens and maintains full working pressure behind the piston, and the port 16 does the same when it is again uncovered by the piston.

In. the arrangement shown in Fig. III the non-return valve 18 itself controls the compression of the air. It is fitted in the main inlet 9 of the machine, beyond both the distributing valve 7 and the port 16 so that the air going to either the valve 7 or the port 16 passes said valve 18. The latter extends to the rear end of the cylinder.

The method of operation is that while the valve 7 is in its forward position, air

is displaced from the rear cylinder 2 and;

passes into the front cylinder 1 together with further air fromthe inlet 9. Upon the valve 7 being thrown over to out 011 the supply to the front cylinder, the air which is being displaced from the rear cylinder tends to pass back into the inlet 9. This closes the valve 18 and causes the air in the rear cylinder chamber 2 and the port 16 to be compressed. During the ensuing forward stroke the valve 18 reopens and passes further air to the rear cylinder as soon as the pressure therein falls to that of the supply.

In the modification shown in Fig. IV the non-return valve 18 is positioned in the port 16, which is not covered by the piston. The

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result is that compression begins in the rear cylinder immediately on the return stroke. This reduces the back kick of the machine but tends to prolong the cycle, as compared withthe Fig. I construction.

The powerful reversal of the piston enables a much higher piston velocity than usual to be used during the rearward cylinder and results in a 7 1. In a rock drill channeling machine or I I coal cutter, the combination with the cylinder and piston of passage means arranged within said cylinder and adapted to maintain continued fluid pressure on the rear working piston area, a non-return valve in I V said passage means, and a distributing valve means adapted to supply working fluid to the front cylinder chamber during the rearward stroke and thereafter immediately to exhaust said chamber. I I

2. In a rock drill channeling machine or coal cutter, the combination with the cylin-' der of a differential piston having its rear working pressure face smaller than its front working pressure face, passage means arranged within said cylinder and adapted to r maintain continued fluid pressure on said rear piston area, a non-return valve in said passage means, and a distributing valve means adapted to supply working fluid to the front cylinder chamber during the rearward stroke and thereafter immediately to exhaust said chamber. 7 1

. 3. In a rock drill channeling machine or coal cutter, the combination with the cylinder and piston of passage means within said cylinder such passage extending into the rear cylinder chamber beyond the rear limit of the pistons travel and arranged to maintain continued fluid pressure on therear working piston area, a non-return valve in said passage means, and a distributing valve means adapted to supply working fluid to the front cylinder chamber during the rearward stroke and thereafter imemdiately to exhaust said chamber. i

In testimony whereof I aflix' my signature.

WILHELM MAUSS.

"commissioner of Patents, 

